<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>选择器</title>
    <style>
        /*元素选择器*/
        /*宽泛优先级最低*/
        div{
           color: aqua;
        }
        /*类选择器*/
        /*类名不唯一,优先级其次*/
        .cls{
            color: green;
        }
        /*id选择器*/
        /*id唯一,优先级最高*/
        #d1{
            color: blue;
        }
        #d2{
            color: red;
        }
    </style>
</head>
<body>
<div>div</div>
<div class="cls">div1</div>
<div id="d1">div2</div>
<div id="d2">div3</div>
</body>
</html>